Cooking food products such as whole muscle meats in cooking bags has recently gained popularity. Traditional cooking bags can be generally categorized into two groups. The first group includes cooking bags used to cook meats at temperatures primarily below the boiling point of water, i.e., less than 212° F. These bags are usually multi-layered and consist of polyethylene, either co-extruded or laminated, with other barrier type polymers such as nylon, ethylene-vinyl alcohol (EVOH), or polyester. They are relatively easy to heat seal because they are sealed using a polyethylene heat seal layer which has a low melt point. This low melt point, however, leads to other drawbacks. First, cooking at a temperature above the melt point leads to degradation/failure of the bag and destruction of the food product being cooked. Furthermore, Food and Drug Administration regulations require that cooking of food products in these materials be performed in temperatures below the boiling point of water. Accordingly, the cooking range for these bags is typically between 180° F. and 210° F.
The second group of cooking bags are high temperature cooking bags. These bags usually consist of a single layer of film comprising either 100% nylon or 100% oriented polyester. Typically the film is very thin, i.e., about 1 mil thick. The drawbacks of these products are numerous. First, they are not readily heat sealable as it is extremely difficult to get a good hermetic seal at a meat packing plant with films comprising 100% nylon or 100% oriented polyester. Second, because the bags are so thin, they lack durability and can easily be torn or ripped during handling. Third, because these bags consist of a single layer film, they do not contain both good gas barrier properties and good moisture barrier properties. For example, nylon bags have good gas barrier properties but poor moisture barrier properties. Accordingly, nylon bags are not useful for long-term storage of non-frozen foods. Polyester bags, for example, have good moisture barrier properties, but less than optimal gas barrier properties. As such, products stored in polyester bags can be easily fouled by migration of undesired gases and odors into the bag.
A high temperature bag that can be used for high temperature processes above 212° F. is desirable. In addition, a multilayer film or a high temperature bag, having one or more of the following properties including readily heat sealed; durable enough to withstand handling during packaging, transport, and cooking; good gas barrier properties; and good moisture barrier properties would also be desirable. Furthermore, a multi-layer cooking bag that can be used for high temperature processes such as high temperature cooking of food products would also be desirable.